Spiral bevel gears are widely used as important parts of various mechanical equipment, such as machine tools, airplanes, ships, watches and fans used in daily life. Gear can also be divided into cylindrical gear,, non-circular gear, rack, worm and according to its shape; , , herringbone gear, curve gear according to the shape of the tooth line; external gear and internal gear according to the surface of the tooth; gear, cutting gear, rolling gear, sintering gear according to the manufacturing method.
The gear with soft tooth surface has low bearing capacity, but it is easy to manufacture and has good running in performance. It is mostly used in general machinery with no strict restrictions on transmission size and weight and small production. Because of the heavy burden of the small gear in the matched gear, the hardness of the small gear surface is generally higher than that of the large gear in order to make the working life of the large and small gears approximately equal.
The bearing capacity of hard gear is high, it is after gear finishing cutting, then quenching, surface quenching or carburizing quenching treatment, in order to improve the hardness. But in the heat treatment, the gear will inevitably deform, so after the heat treatment, it must be grinded, grinded or finely cut to eliminate the error caused by the deformation and improve the accuracy of the gear.
The commonly used steels forare quenched and tempered steel, quenched steel, carburized and quenched steel and nitrided steel. The strength of cast steel is slightly lower than that of forged steel, which is commonly used for gears with larger size; the mechanical property of gray cast iron is poor, which can be used in the open gear drive with light load; nodular cast iron can partially replace steel to make gears; plastic gears are mostly used in places with light load and low noise requirements, and the gears matched with them are generally steel gears with good thermal conductivity.
The development of gear theory and manufacturing technology will further study the mechanism of gear tooth damage, which is the basis of establishing a reliable strength calculation method. It is the theory of improving gear bearing capacity and prolonging gear life to carry out gear tooth profile modification, so as to improve the stability of gear operation, and increase the contact area of gear teeth when fully loaded, so as to improve the bearing capacity of gear.